Redis缓存Object，List对象

一、到目前为止（jedis-2.2.0.jar），在Jedis中其实并没有提供这样的API对对象，或者是List对象的直接缓存，即并没有如下类似的API

jedis.set(String key, Object value)

jedis.set(String key, List<M> values)

而更多的API是类似于 jedis.set(String key, String value)或者jedis.set(String key, String ... value)

那如果我们想缓存对象，怎么办呢？

二、通过研究Jedis的API，我们发现其提供了这样的API

jedis.set(byte[], byte[]),

通过这个API，很显然我们能够实现

jedis.set(String key, Object value)

jedis.set(String key, List<M> values)

我们需要关注的就是在cache的时候将Object和List对象转换成字节数组并且需要提供将字节数组转换成对象返回。

三、考虑到扩展性，设计了3个类，抽象父类SerializeTranscoder， 子类ListTranscoder和ObjectsTranscoder 以及一个Unit test 类 用于模拟对象，list对象和字节数组的转换，即Serialize和de-searilize的过程。

1. SerializeTranscoder

package com.chuanliu.platform.activity.basic.util.serialize;

import java.io.Closeable;

import org.apache.log4j.Logger;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  josh_wang23@hotmail.com
 */
public abstract class SerializeTranscoder {

  protected static Logger logger = Logger.getLogger(SerializeTranscoder.class);

  public abstract byte[] serialize(Object value);

  public abstract Object deserialize(byte[] in);

  public void close(Closeable closeable) {
    if (closeable != null) {
      try {
        closeable.close();
      } catch (Exception e) {
         logger.info("Unable to close " + closeable, e);
      }
    }
  }
}

2. ListTranscoder

package com.chuanliu.platform.activity.basic.util.serialize;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import com.chuanliu.platform.activity.basic.util.LoggerUtils;

/**
 * Case 1.
 * Jedis does not support cache the Object directly, the Objects needed to be
 * serialized and de-serialized
 *
 * Case 2.
 * coming very soon...
 *
 * @author Josh Wang(Sheng)
 *
 * @email  josh_wang23@hotmail.com
 */
public class ListTranscoder<M extends Serializable> extends SerializeTranscoder {

  @SuppressWarnings("unchecked")
  public List<M> deserialize(byte[] in) {
    List<M> list = new ArrayList<>();
    ByteArrayInputStream bis = null;
    ObjectInputStream is = null;
    try {
      if (in != null) {
        bis = new ByteArrayInputStream(in);
        is = new ObjectInputStream(bis);
        while (true) {
          M m = (M)is.readObject();
          if (m == null) {
            break;
          }

          list.add(m);

        }
        is.close();
        bis.close();
      }
    } catch (IOException e) {
      LoggerUtils.error(logger, String.format("Caught IOException decoding %d bytes of data",
        in == null ? 0 : in.length) + e);
  } catch (ClassNotFoundException e) {
      LoggerUtils.error(logger, String.format("Caught CNFE decoding %d bytes of data",
        in == null ? 0 : in.length) + e);
  }  finally {
      close(is);
      close(bis);
    }

    return  list;
  }

  @SuppressWarnings("unchecked")
  @Override
  public byte[] serialize(Object value) {
    if (value == null)
      throw new NullPointerException("Can't serialize null");

    List<M> values = (List<M>) value;

    byte[] results = null;
    ByteArrayOutputStream bos = null;
    ObjectOutputStream os = null;

    try {
      bos = new ByteArrayOutputStream();
      os = new ObjectOutputStream(bos);
      for (M m : values) {
        os.writeObject(m);
      }

      // os.writeObject(null);
      os.close();
      bos.close();
      results = bos.toByteArray();
    } catch (IOException e) {
      throw new IllegalArgumentException("Non-serializable object", e);
    } finally {
      close(os);
      close(bos);
    }

    return results;
  }

}

3. ObjectsTranscoder

package com.chuanliu.platform.activity.basic.util.serialize;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import com.chuanliu.platform.activity.basic.util.LoggerUtils;

/**
 * Case 1.
 * Jedis does not support cache the Object directly, the Objects needed to be
 * serialized and de-serialized
 *
 * Case 2.
 * coming very soon...
 *
 * @author Josh Wang(Sheng)
 *
 * @email  josh_wang23@hotmail.com
 */
public class ObjectsTranscoder<M extends Serializable> extends SerializeTranscoder {

  @SuppressWarnings("unchecked")
  @Override
  public byte[] serialize(Object value) {
    if (value == null) {
      throw new NullPointerException("Can't serialize null");
    }
    byte[] result = null;
    ByteArrayOutputStream bos = null;
    ObjectOutputStream os = null;
    try {
      bos = new ByteArrayOutputStream();
      os = new ObjectOutputStream(bos);
      M m = (M) value;
      os.writeObject(m);
      os.close();
      bos.close();
      result = bos.toByteArray();
    } catch (IOException e) {
      throw new IllegalArgumentException("Non-serializable object", e);
    } finally {
      close(os);
      close(bos);
    }
    return result;
  }

  @SuppressWarnings("unchecked")
  @Override
  public M deserialize(byte[] in) {
    M result = null;
    ByteArrayInputStream bis = null;
    ObjectInputStream is = null;
    try {
      if (in != null) {
        bis = new ByteArrayInputStream(in);
        is = new ObjectInputStream(bis);
        result = (M) is.readObject();
        is.close();
        bis.close();
      }
    } catch (IOException e) {
      LoggerUtils.error(logger, String.format("Caught IOException decoding %d bytes of data",
          in == null ? 0 : in.length) + e);
    } catch (ClassNotFoundException e) {
      LoggerUtils.error(logger, String.format("Caught CNFE decoding %d bytes of data",
          in == null ? 0 : in.length) + e);
    } finally {
      close(is);
      close(bis);
    }
    return result;
  }
}

4. TestSerializerTranscoder

package com.chuanliu.platform.activity.basic.util;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

import com.chuanliu.platform.activity.basic.util.serialize.ListTranscoder;
import com.chuanliu.platform.activity.basic.util.serialize.ObjectsTranscoder;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  josh_wang23@hotmail.com
 */
public class TestSerializerTranscoder implements Serializable {

  private static final long serialVersionUID = -1941046831377985500L;

  public TestSerializerTranscoder() {

  }

  @Test
  public void testObject() {
    List<TestUser> lists = buildTestData();

    TestUser userA = lists.get(0);

    ObjectsTranscoder<TestUser> objTranscoder =  new ObjectsTranscoder<>();

    byte[] result1 = objTranscoder.serialize(userA);

    TestUser userA_userA = objTranscoder.deserialize(result1);

    System.out.println(userA_userA.getName() + "\t" + userA_userA.getAge());
  }

  @Test
  public void testList() {
    List<TestUser> lists = buildTestData();

    ListTranscoder<TestUser> listTranscoder = new ListTranscoder<>();

    byte[] result1 = listTranscoder.serialize(lists);

    List<TestUser> results = listTranscoder.deserialize(result1);

    for (TestUser user : results) {
      System.out.println(user.getName() + "\t" + user.getAge());
    }

  }

  private static List<TestUser> buildTestData() {
    TestSerializerTranscoder tst = new TestSerializerTranscoder();
    TestUser userA =  tst.new TestUser();
    userA.setName("lily");
        userA.setAge(25);

        TestUser userB = tst.new TestUser();  

        userB.setName("Josh Wang");
    userB.setAge(28);

        List<TestUser> list = new ArrayList<TestUser>();
        list.add(userA);
        list.add(userB);  

        return list;
    }

  class TestUser implements Serializable {
    private static final long serialVersionUID = 1L;

      private String name;

      private int age;

      public String getName() {
        return name;
      }

      public void setName(String name) {
        this.name = name;
      }

      public int getAge() {
        return age;
      }

      public void setAge(int age) {
        this.age = age;
      }

    }

}

四、通过以上几步后，即可使用Jedis的API进行对象的缓存并将从缓存中返回的二进制数组转换成原始的对象或者是List对象了。